Abstract

Time-resolved electron shadowgraphy measurement was performed in infrared 300 ps laser ablation of a copperfilm in order to investigate expanding plasma into vacuum with space-charge separation. The probe-electron pulse was generated by intense femtosecond laserirradiation on a tungsten bulk target. Time-resolved electron shadowgraphs showed evolving “bright” and “shadow” plumes with expanding speeds of 970 and 110 km/s, when the laser intensity was These are attributed to be space-charge separation field and ion plume, respectively.